Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[karo-tx-linux.git] / arch / arc / include / asm / smp.h

diff --git a/arch/arc/include/asm/smp.h b/arch/arc/include/asm/smp.h
index 4341f3ba7d921f7662596c6c32b16417a08e4b27..c4fb211dcd25bef135c78ea0683e71d9259a8c20 100644 (file)
--- a/arch/arc/include/asm/smp.h
+++ b/arch/arc/include/asm/smp.h
@@ -9,6 +9,58 @@
 #ifndef __ASM_ARC_SMP_H
 #define __ASM_ARC_SMP_H
 
+#ifdef CONFIG_SMP
+
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/threads.h>
+
+#define raw_smp_processor_id() (current_thread_info()->cpu)
+
+/* including cpumask.h leads to cyclic deps hence this Forward declaration */
+struct cpumask;
+
+/*
+ * APIs provided by arch SMP code to generic code
+ */
+extern void arch_send_call_function_single_ipi(int cpu);
+extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
+
+/*
+ * APIs provided by arch SMP code to rest of arch code
+ */
+extern void __init smp_init_cpus(void);
+extern void __init first_lines_of_secondary(void);
+extern const char *arc_platform_smp_cpuinfo(void);
+
+/*
+ * API expected BY platform smp code (FROM arch smp code)
+ *
+ * smp_ipi_irq_setup:
+ *     Takes @cpu and @irq to which the arch-common ISR is hooked up
+ */
+extern int smp_ipi_irq_setup(int cpu, int irq);
+
+/*
+ * struct plat_smp_ops - SMP callbacks provided by platform to ARC SMP
+ *
+ * @info:              SoC SMP specific info for /proc/cpuinfo etc
+ * @cpu_kick:          For Master to kickstart a cpu (optionally at a PC)
+ * @ipi_send:          To send IPI to a @cpumask
+ * @ips_clear:         To clear IPI received by @cpu at @irq
+ */
+struct plat_smp_ops {
+       const char      *info;
+       void            (*cpu_kick)(int cpu, unsigned long pc);
+       void            (*ipi_send)(void *callmap);
+       void            (*ipi_clear)(int cpu, int irq);
+};
+
+/* TBD: stop exporting it for direct population by platform */
+extern struct plat_smp_ops  plat_smp_ops;
+
+#endif  /* CONFIG_SMP */
+
 /*
  * ARC700 doesn't support atomic Read-Modify-Write ops.
  * Originally Interrupts had to be disabled around code to gaurantee atomicity.
@@ -18,10 +70,52 @@
  *
  * (1) These insn were introduced only in 4.10 release. So for older released
  *     support needed.
+ *
+ * (2) In a SMP setup, the LLOCK/SCOND atomiticity across CPUs needs to be
+ *     gaurantted by the platform (not something which core handles).
+ *     Assuming a platform won't, SMP Linux needs to use spinlocks + local IRQ
+ *     disabling for atomicity.
+ *
+ *     However exported spinlock API is not usable due to cyclic hdr deps
+ *     (even after system.h disintegration upstream)
+ *     asm/bitops.h -> linux/spinlock.h -> linux/preempt.h
+ *             -> linux/thread_info.h -> linux/bitops.h -> asm/bitops.h
+ *
+ *     So the workaround is to use the lowest level arch spinlock API.
+ *     The exported spinlock API is smart enough to be NOP for !CONFIG_SMP,
+ *     but same is not true for ARCH backend, hence the need for 2 variants
  */
 #ifndef CONFIG_ARC_HAS_LLSC
 
 #include <linux/irqflags.h>
+#ifdef CONFIG_SMP
+
+#include <asm/spinlock.h>
+
+extern arch_spinlock_t smp_atomic_ops_lock;
+extern arch_spinlock_t smp_bitops_lock;
+
+#define atomic_ops_lock(flags) do {            \
+       local_irq_save(flags);                  \
+       arch_spin_lock(&smp_atomic_ops_lock);   \
+} while (0)
+
+#define atomic_ops_unlock(flags) do {          \
+       arch_spin_unlock(&smp_atomic_ops_lock); \
+       local_irq_restore(flags);               \
+} while (0)
+
+#define bitops_lock(flags)     do {            \
+       local_irq_save(flags);                  \
+       arch_spin_lock(&smp_bitops_lock);       \
+} while (0)
+
+#define bitops_unlock(flags) do {              \
+       arch_spin_unlock(&smp_bitops_lock);     \
+       local_irq_restore(flags);               \
+} while (0)
+
+#else /* !CONFIG_SMP */
 
 #define atomic_ops_lock(flags)         local_irq_save(flags)
 #define atomic_ops_unlock(flags)       local_irq_restore(flags)
@@ -29,6 +123,8 @@
 #define bitops_lock(flags)             local_irq_save(flags)
 #define bitops_unlock(flags)           local_irq_restore(flags)
 
+#endif /* !CONFIG_SMP */
+
 #endif /* !CONFIG_ARC_HAS_LLSC */
 
 #endif